Tips for installing a level wooden floor

My workshop/garage appears to have been a carport that was enclosed at some point. Pretty horrible place. I've slowly been turning it into somewhere I'd like to be.

Major problem at the moment is the floor is that awful 70's pebble-dash stuff that looks like someone with diarrhoea has sprayed the whole area, and it has a significant slope - presumably for water runoff originally. Drop something small., and it's usually gone forever - it's virtually impossible to find a lost screw or nail on that stuff (although my very expensive car tyres seem to find them pretty well...:~)

Sometime in the next year or two, a Man will come and do some proper reno work which will add shop space and additional car parking, and make everything level and clean.

In the meantime there's a little 2m x 2.8m annex that I want to turn into a level-floored work area. The drop over the 2.8m is 16.5cm - like I said, it's a significant slope. I think the easiest temporary floor solution would be a wooden one.

I'm keen to use up a stack of 'repurposed' wood I have lying around - roadside collections, pallets etc. It's likely to be mostly pine (although my wood-identification skillz only extend to 'dark' and 'light' wood!)
It will give me a chance to practice with the new toys - table saw, thicknessing, routing tongue and groove, glue ups and so on. I know it would be easier to buy properly treated wood and sheeting, but I'm anti excessive consumption and waste.

I'm newish to Straya, and I believe there are small fiends that eat wood here in NSW, so I need some advice on countering the beasts. Would a sheet of plastic or semi-permeable membrane of some sort over the pebble dash floor be enough to protect the new floor?

Any advice/tips/pitfalls for building the subframe before I start? 400mm joist spacing?

No amount of plastic will stop them and once they get into anything that resembles a building they will eat any and everything, and find their way into your house, they will even eat the paper off plasterboard to get to other timber. They love a bit of moister and dark places with poor ventilation.
All your roadside rescued timber will not be treated against white ants. The only viable solution even though you say it is temporary is to use H3 or H4 treated timber and build your framework out of that then use red tongue sheet flooring, it is termite resistant.

They are now making an insecticide impregnated plastic, both in sheet and strip damp course form.

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Originally Posted by rustynail

They are now making an insecticide impregnated plastic, both in sheet and strip damp course form.

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Correct, they have been around for about 25 yrs. Going by the original post, I suspect it will be an interesting exercise for someone not au fait with correct installation.

For my two cents worth, just go ahead! If it is supposed to be temporary, it's pretty safe bet that nothing will eat it all away in 2 seasons, and most international palettes/pallets (too lazy 2 check) are treated against zoostowaways. If its light, and was free, it's probably very fast-grown pine, and preety weak, so place any "joist"-type supports at very conservative (close) centres. Don't try to get it perfect, but do try to get it level. and....bizarre as it might sound, old carpet is actually not so terrible as a finish of you have an old vacuum around the place. Make it sufficiently rustic that you can't allow yourself to keep it. :) Good luck.

Laying out a treat for white ants anywhere near the house could cost you dearly. Kind of like an open invite. The cost of proper treated material will be very small compared to an infestation of the house. Looking at thousands for the pest control guys alone before you even start on the repair work. Been there and paid the price. Noticed the beasties in a timber fence so we pulled it down. 2 years later had to pull out the kitchen (only 2 wears old) and half the lounge replace all the studs and gyprock. After the expensive treatment of course.
Regards
John

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Originally Posted by billrule

For my two cents worth, just go ahead! If it is supposed to be temporary, it's pretty safe bet that nothing will eat it all away in 2 seasons, and most international palettes/pallets (too lazy 2 check) are treated against zoostowaways. If its light, and was free, it's probably very fast-grown pine, and preety weak, so place any "joist"-type supports at very conservative (close) centres. Don't try to get it perfect, but do try to get it level. and....bizarre as it might sound, old carpet is actually not so terrible as a finish of you have an old vacuum around the place. Make it sufficiently rustic that you can't allow yourself to keep it. :) Good luck.

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Your tag line sums it up well

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Originally Posted by rwbuild

Your tag line sums it up well

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Haha... yes, but ironically perhaps, I HAD intended to direct Bernmc to YOUR tagline for inspiration! In my own defence, looking around me, I see quite a lot of stuff that exists in more than theory.

If you consider using the plastic membrane I'd put something tough over the pebble first dash otherwise I'd be worried it would puncture the membrane. Also agree this is a short term solution.

BTW 2 years is more than enough time for termites to eat right though a subfloor. At our place the blighters came from 13m away and largely destroyed a 3m long section of stud topped by bay window frame, and they were up into the roof timbers in just over 8 months after the extension was completed. The builder accepted that the courses of brick under the stud wall were not high enough above the ground so the termites could enter the stud wall directly from under the surrounding brick paving. When we ripped the paving up around the stud wall there were literally termite tracks ~ 8 termites wide going both to and from their entry points. The builder added extra courses and rebuilt the whole wall and replaced roofing timbers but he would not repaint the wall as painting was not included in the original contract and I was left to do it again..

Well, it’s prompted me to get a bug man to come and inspect the place to start with. Seems it’s safest to go H3/H4. I’m not confident about the ‘conversion’ of carport to garage - suspect corners may have been cut...

I think I have two options for building the floor: Picture shows the garage, with the small annex that I'm going to level.

I need to raise the floor by 150mm across the 2.8m length.

So, I could (A) cut my joists at the angle of the floor. Start off from zero, up to 150mm at the low end, and then red tongue boards on top. This will give me the least difference in floor levels between the new wood floor and the rest of the garage. Bunnings do 200mmx50mm H4 in 3m lengths, so this is doable. But do I need to treat cut edges with TermiteBeGone?

Or I could do the traditional (B) and build a simple subframe out of H3 2x4's or 2x6's = whatever's available, and then level the frame. No angled cutting to do, (fewer cut edges if I need to treat them?), but the whole floor is then going to be an additional 100-150mm + boards above the rest of the garage at its lowest point, and 150mm + that at the other...

Attachment 451563

An easier and possibility cheaper solution is to use galvanised RHS or SHS and fix your sheeting to it with self drilling screws
you could start just 25mm higher than your current high point and go level from there

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Originally Posted by Beardy

An easier and possibility cheaper solution is to use galvanised RHS or SHS and fix your sheeting to it with self drilling screws
you could start just 25mm higher than your current high point and go level from there

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I'll investigate this - and see if there are any easy local suppliers